Start by grating your cheddar or jalapeño jack cheese fresh—this ensures a smoother melt. Dice your small purple onion finely so it blends evenly throughout the dip. Use full-fat cream cheese straight from the fridge, but don’t worry—microwaving will soften it quickly.
Place the cream cheese, grated cheese, mayonnaise, and diced onion directly into your shallow baking dish. There’s no need to pre-mix in a bowl. Use a spoon to slightly level the ingredients, but don’t stir yet. This saves you from extra dishes and keeps everything easy.
Microwave the dish on high for about 2 minutes. This step softens the cream cheese and melts the shredded cheese slightly, making it easier to mix. Remove from the microwave carefully and stir the ingredients until well combined and smooth.
Transfer the dish to your preheated oven and bake at 350°F (175°C) for 20 minutes. The top should be lightly browned and bubbly. The edges may be slightly crisp—this adds extra flavor and texture.
Serve the dip hot, right from the baking dish. It pairs perfectly with Wheat Thins or Frito’s Scoops, but you can also try pita chips or sliced veggies. For best results, enjoy it while it’s still warm and gooey.